Injection apparatus for industrial machine

ABSTRACT

An injection apparatus for industrial machine capable of high speed injection is provided with an injection barrel communicating with a cavity formed by at least a pair of mold dies and introducing mold material to an end portion on communicating side of the barrel, a screw for injection inserted in the barrel in which the screw is capable of reciprocating motion so as to inject and fill the mold material into the cavity, a support means holding an end of the screw opposite to the cavity and capable of moving in the direction of the reciprocating motion, a first drive mechanism including an electric servomotor for moving the support means in the direction of the reciprocating motion and a second drive mechanism for moving the first drive mechanism in the direction of the reciprocating motion.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an injection apparatus forindustrial machines such as plastic injection molding machine or diecasting machine, specifically to the injection apparatus capable ofmolding an article with high quality by improving injection speedthereof.

[0003] 2. Description of Related Art

[0004] The quality of mold article is affected through injection speedand pressure during injecting and filling in the industrial machine inwhich the mold material such as melt resin or metal is injected andfilled into a cavity formed in a mold die of the machine.

[0005] Incidentally, the cavity shape in the mold die is of variouskinds in accordance with mold articles. Then function and capability onthe injection speed, pressure and etc. required in the injectionapparatus greatly vary.

[0006] On the other hand, because of requirement for noiseless,cleanness good controllability and spread of powerful servomotor forseveral years, demand for the industrial machine rapidly changes from ahydraulic drive system to an electric drive system.

[0007] An injection apparatus for injection molding machine of the typewith the electric drive system now spreading, is provided with a screwsupported with the one end capable of rotating to supply resin melt andkneaded in the barrel to the mold die (cavity). A support member of thescrew is capable of linear movement by means of linear guides.

[0008] A drive force is supplied to the support member, which isgenerated by converting rotational movement of an electric motor as adrive source to linear movement using a pair of ball screw and ball nutarrangement.

[0009] There are two methods for the conversion. The one is a ballnut-drive method, and the other is a ball screw-drive method. In theball nut-drive method, the support member is connected to the ball screwengaging with the ball nut. The ball nut is rotated by the electricmotor directly or indirectly coupled to it. In the ball screw-drivemethod, the support member is connected to the ball nut engaging withthe ball screw. The ball screw is rotated by the electric motor directlyor indirectly coupled to it.

[0010] Besides the ball screw and ball nut arrangement, there exists aninjection apparatus with the support member connected to a mechanism inwhich a linear movement is produced through a drive force generated byelectromagnetic force like a linear motor, or with a plunger instead ofthe screw.

[0011] Even in such injection apparatus for injection molding machine ofthe type with the electric drive system now spreading, there is still alimitation to the request for a high speed injection necessary to moldthe mold material mentioned above and produce an mold article with highquality.

[0012] Accordingly, an object of the present invention is to provide aninjection apparatus for industrial machine capable of high speedinjection.

[0013] To achieve the object the injection apparatus for industrialmachine of the present invention is provided with an injection barrelcommunicating with a cavity formed by at least a pair of mold dies andintroducing mold material to an end portion on communicating side of thebarrel, a screw for injection inserted in the barrel in which the screwis capable of reciprocating motion so as to inject and fill the moldmaterial into the cavity, a support means holding an end of the screwopposite to the cavity and capable of moving in the direction of thereciprocating motion, and a first drive mechanism for moving the supportmeans in the direction of the reciprocating motion. The injectionapparatus is further provided with a second drive mechanism for movingthe support means or the first drive mechanism in the direction of thereciprocating motion.

[0014] In the case a plunger may be used instead of the screw. Also, inthe case at least either one of the first drive mechanism or the seconddrive mechanism may be constructed to have an electric servomotor, and aball screw and ball nut arrangement that converts rotating motion of therotary drive axis of the electric servomotor to linear motion. Then incase of constructing the first drive mechanism by means of the electricservomotor, and the ball screw and ball nut arrangement, the seconddrive mechanism may be constructed to be parallel with the ball screw ofthe first drive mechanism, and also may be constructed in series orconcentrically to the axis line of the ball screw.

[0015] Further, at least one of the first and second drive mechanismsmay be constructed by means of either one or combination of rollerscrew, linear motor and hydraulic or pneumatic actuator.

[0016] The injection speed can be greatly increased by moving the firstdrive mechanism through the second drive mechanism. In this case if aplurality of the first drive mechanism and the second drive mechanismare arranged to be parallel, injection drive force can be greatlyincreased, too.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features, and advantages of thepresent invention will be made more apparent from the description ofpreferred embodiments with reference to the accompanying drawingswherein:

[0018]FIG. 1 is a front view of the injection apparatus for injectionmolding machine of the type with the electric drive system illustrativeof an embodiment of the present invention.

[0019]FIG. 2 is a front view of the injection apparatus of anotherembodiment of the present invention illustrative of an arrangement ofanother linear drive mechanism at the most right end portion of guiderods extending through a support member to the right, instead of asupport plate in FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

[0020] The preferred embodiments will be explained below with referenceto the accompanying drawings.

[0021]FIG. 1 shows a front view of the injection apparatus for injectionmolding machine of the type with the electric drive system of thepresent invention.

[0022] As shown in FIG. 1, there is provided an injection apparatusarranged over a structural member 10 which is stationed on a base (notshown) of the injection molding machine of the type with the electricdrive system.

[0023] Reference numeral 12 designates a barrel that forms an injectiontube, and supported by a barrel support member 16. At the most left endof the barrel 12 a nozzle NZ is mounted. In the barrel 12, a screw 14 asa pushing member is inserted so as to be capable of reciprocating motionin the direction of the screw axis. The most right end of the screw 14is held on a screw support member 20 slidably supported by a guide rod18 so that the screw 14 is capable of rotating and restricted frommoving in the direction of the screw axis.

[0024] Further, the lower portion of the barrel support member 16 isfixedly mounted through a member 22 on the structural member 10.Incidentally, the screw support member 20 defines a support member ofthe present invention.

[0025] Reference numeral 18 designates a guide rod, the left end ofwhich is fixedly connected to the barrel support member 16. The rightend of the guide rod 18 is slidably mounted on a support member 32 whichis a part of a drive mechanism generating drive force for moving thescrew 14 in the axis direction through the screw support member 20. Theguide rod 18 is mounted at each corner portion of the barrel supportmember 16.

[0026] Reference numeral 24 designates an electric servomotor mounted onthe screw support member 20. The electric servomotor 24 executes acharging process for melt resin by rotating the screw 14 through arotation transmission mechanism (not shown). In the support member 32, aball nut 28 is mounted so that the ball nut 28 is capable of rotatingand restricted from moving in the direction of the axis.

[0027] Reference numeral 26 designates a ball screw fixedly connected atthe right side portion of the screw support member 20 through fittings30, the screw portion of which engages with the ball nut 28.Accordingly, rotation of the ball nut 28 causes the screw 14 to advanceand retract in the barrel 12 as the screw 14 is restricted from movingin the axis direction to the screw support member 20.

[0028] Reference numeral 34 designates an electric servomotor as a drivesource to drive the screw 14. A timing belt 36 is mounted between apulley mounted on the rotary drive axis of the servomotor 34 and apulley 38 stationed in the right side of the support member 32.

[0029] The pulley 38 is one with the ball nut 28 and rotatably mountedon the support member 32. Incidentally, the ball screw 26, the ball nut28, the support member 32, the electric servomotor 34, the timing belt36 and pulley 38 define a first drive mechanism of the presentinvention. Though only one first drive mechanism is illustrated in FIG.1, a plurality of the first drive mechanisms can be stationed inparallel. Reference numeral 40 designates a reinforcement member for thesupport member 32.

[0030] The relationship between the ball screw 26 and the ball nut 28 inview of drive force transmission may be reversed. In the case the ballnut 28 is fastened to the screw support member 20, and the ball screw 26is mounted on the support member 32 rotatably but with restricted frommoving in the direction of the screw axis.

[0031] The above description corresponds to the conventional mechanismon the injection apparatus for injection molding machine of the typewith the electric drive system except that each right end of the guiderod 18 is fastened to the support member 32.

[0032] In the conventional machine with such a mechanism, resin is meltand kneaded in the barrel 12, and introduced at one end portion of thebarrel 12. Then it is injected into a cavity at injection speed VI ofthe screw 14.

[0033] Hereinafter, a mechanism to be add to the conventional mechanismwill be explained.

[0034] On the structural member 10 there is provided with a linear guide46 parallel to the guide rod 18, on which a support plate 50 mountingguide members 62 and 63 at its lower end is movably stationed. Thesupport member 32 and the reinforcement member 40 are fastened by bolts42 to the surface near the right end portion of the support plate 50.Also, on the surface near left end of the support plate 50 a linearguide 48 parallel to the guide rod 18 is stationed, and the screwsupport member 20 is movably guided by a guide member 64 mounted at thelower end of the screw support member 20.

[0035] Further, under the support plate 50 there is provided with anelectric servomotor 44 fastened on the structural member 10. The rotarydrive axis of the electric servomotor 44 is connected through a coupling60 to a ball screw 54 rotatably supported by bearings 58 and 59.

[0036] The ball screw 54 engages with a ball nut 56 which is mounted ona support member 52 formed at the under portion near the center of thesupport plate 50.

[0037] The support member 52 restricts the ball nut 56 from rotating andmoving in the direction of the axis.

[0038] In such an arrangement, as the electric servomotor 44 rotates theball screw 54 rotates and as the result, the support plate 50 movesrectilinearly. Incidentally, the support plate 50, the electricservomotor 44, the ball screw 54, the ball nut 56, the support member52, bearings 58 and 59, and the coupling 60 define a second drivemechanism of the present invention. Because the support member 32 isfastened to the support plate 50, the screw 14 moves in the leftdirection rectilinearly through the support member 32, the ball nut 28,the ball screw 26 and the screw support member 20 as the support plate50 moves in the left direction rectilinearly, even when the electricservomotor 34 stops rotating. Then, further in case that the electricservomotor 34 is driven and the screw support member 20 moves in thesame direction, the moving velocity of the screw 14 in the leftdirection is given as the resultant, that is, V1+V2 of each velocity V1,V2 based on rotary drive force that both of electric servomotors 34, 44generate. In the case the stroke length of the screw 14 increases by therange of linear movement of the support plate 50.

[0039] In FIG. 1, only one drive mechanism is provided under the supportplate 50, which is comprised of the electric servomotor 44, the ballscrew 54, the ball nut 56 and etc. However, a plurality of such drivemechanisms may be provided on the structural member 10 wherein each theelectric servomotor is controlled in synchronization with each other.

[0040] It is possible to decentralize or share a required drive force byarranging such plurality of drive mechanisms so that members such as theelectric servomotor the ball screw and the ball nut in the drivemechanism can be downsized and also used for long time.

[0041] In the above description of FIG. 1, the drive mechanism forreciprocating motion of the screw 14 and the support plate 50 isprovided with an electric servomotor and a conversion unit by means of aball screw and ball nut arrangement. However, a roller screw, a linearmotor, or hydraulic and pneumatic actuators can be substituted for them.

[0042]FIG. 2 is illustrative of a second embodiment of the presentinvention, and also illustrative of an arrangement of another lineardrive mechanism at the most right end portion of guide rod 18 extendingthrough the support member 32 to the right, instead of the support plate50 in FIG. 1. Incidentally, in FIG. 2, detailed description of eachelement corresponding to the reference numerals identical to those inFIG. 1 is omitted because of already explained in FIG. 1. Similarly, inFIG. 2 reference numerals 26A, 28A, 30A, 32A, 34A, 36A, and 38A are theelements for functions similar to reference numerals 26, 28, 30, 32, 34,36, and 38 in FIG. 1, respectively. The difference points are such thatthe lower part of the support member 32A in FIG. 2 is fastened on thestructural member 10 and the most end right portions of the guide rods18 are fastened to the support member 32A. Accordingly, in FIG. 2 rotarydrive force transmitted from the electric servomotor 34A to the ball nut28A causes the ball screw 26A to move rectilinearly and as the result,the support member 32 slidably moves on the guide rods 18 rectilinearly.

[0043] In FIG. 2 the ball screw 26A is arranged in series andconcentrically to the ball screw 26. As described in FIG. 1, theelements of numerals 26 to 38 and numerals 26A to 38A may be constructedby means of other roller screw, a linear motor or hydraulic andpneumatic actuators. Furthermore, as to the arrangement for the aboveelements of numerals 26A to 38A it is possible to construct so thatstill another drive mechanism is stationed on the right side of thesupport member 32A, a plurality of drive mechanisms are stationed on theleft side surface of the support member 32A, or those mechanisms arecombined. In the case, however, it should be noticed that arranging aplurality of drive mechanisms in series leads to a space problem becausethe injection apparatus becomes long.

[0044] According to the present invention, there is an advantage thathigh speed injection can be achieved, since the injection apparatus forindustrial machine of the present invention is provided with aninjection barrel communicating with one end of a cavity formed by atleast a pair of mold dies and introducing mold material to an endportion on communicating side of the barrel, a screw for injectioninserted in the barrel in which the screw is capable of reciprocatingmotion so as to inject and fill the mold material into the cavity, asupport means holding an end of the screw opposite to the cavity andcapable of moving in the direction of the reciprocating motion, a firstdrive mechanism for moving the support means in the direction of thereciprocating motion, a second drive mechanism for moving the supportmeans or the first drive mechanism in the direction of the reciprocatingmotion.

[0045] According to the present invention, there is another advantagethat mold articles with high quality can be produced without employingexpensive and powerful electric servomotors since a plurality of thefirst drive mechanisms and the second drive mechanisms are able to bearranged in parallel to increase the drive force on the industrialmachine.

[0046] According to the present invention, there is still anotheradvantage that mold articles of relatively large size can be producedsince injection stroke of the machine lengthens by the stroke of thesecond drive mechanism.

[0047] It should be understood, of course, that the foregoing disclosurerelates only to preferred embodiments of the invention, and that it isintended to cover all changes and modifications of the example of theinvention herein chosen for the purpose of the disclosure which does notconstitute departures from the spirit and scope of the invention setforth in the appended claims.

What is claimed is:
 1. An injection apparatus for industrial machinecomprising; an injection barrel communicating with a cavity formed by atleast a pair of mold dies and introducing mold material to said cavity,a screw for injection inserted in said barrel in which said screw iscapable of reciprocating motion so as to inject and fill said moldmaterial into said cavity, a support means holding an end of said screwopposite to said cavity and capable of moving in a direction of saidreciprocating motion, a first drive mechanism for moving said supportmeans in the direction of the reciprocating motion and a second drivemechanism for moving said support means or said first drive mechanism inthe direction of the reciprocating motion.
 2. In the injection apparatusfor industrial machine as in claim 1, wherein at least either one of thefirst drive mechanism or the second drive mechanism is provided with anelectric servomotor, and a ball screw and ball nut arrangement thatconverts rotating motion of a rotary drive axis of the electricservomotor to linear motion.
 3. In the injection apparatus forindustrial machine as in claim 2, wherein the first drive mechanism isprovided with the electric servomotor, and the ball screw and ball nutarrangement, and the second drive mechanism is arranged to be parallelwith the ball screw of the first drive mechanism.
 4. In the injectionapparatus for industrial machine as in claim 2, wherein the first drivemechanism is provided with the electric servomotor, and the ball screwand ball nut arrangement, and the second drive mechanism is arranged inseries or concentrically to the axis line of the ball screw.
 5. In theinjection apparatus for industrial machine as in claim 1, 2, 3 or 4,wherein at least one of the first drive mechanism and the second drivemechanism is provided with either one or combination of a roller screw,a linear motor and a hydraulic or pneumatic actuator.
 6. In theinjection apparatus for industrial machine as in claim 1, wherein aplunger is used for injecting as a substitution of the screw.
 7. In theinjection apparatus for industrial machine as in claim 1, wherein theindustrial machine is a plastic injection molding machine.